A New Approach to Efficiently Disperse Aggregated Palygorskite Into Single Crystals via Adding Freeze Process Into Traditional Extrusion Treatment

This paper reports a processing technology of natural nanorod materials. Palygorskite is a type of natural nanorod hydrous clay mineral, and its basic unit is about 20-40 nm in diameter and 1-5 ¿m in length. Low-cost single crystals of palygorskite can be produced in mass by simply adding freeze process into traditional extrusion treatment. The dispersion state of palygorskite was investigated by X-ray diffraction (XRD), particle size distribution, SEM, transmission electron microscopy (TEM), and viscosity techniques. The effects of the freeze process and treatment time on the dispersive quality of palygorskite were also studied. The results indicated that the new approach was efficient to disperse palygorskite ore into nanometer-scale particles and the crystal bundles of palygorskite into single crystals. Moreover, the new approach had much lower breakage of the long fine fiber of palygorskite compared with the dry process. The freeze process had remarkable influence on the improvement of the dispersion of palygorskite ore. The viscosity of the sample treated with the freeze process was enhanced twice from 472 to 3894 mpa·s, which was about 2.6 times that of the sample treated without the freeze process. The treated samples showed very uniform fibers about 20-40 nm in width and 1-5 ¿m in length, as observed from TEM, which is in good agreement with the perfect rod-shaped crystals of palygorskite. In addition, the treated samples showed XRD patterns similar to that of the untreated palygorskite ore, which suggests that the treated samples retained their original structure.